In recent years, in audio units such as cassette player, CD (Compact Disc) player or DVDs (Digital Versatile Disc), which are recording and/or reproducing devices, various units of vehicle-mounted specifications come into wide use. In such vehicle-mounted units, there arises a problem that the unit may be stolen while a driver is away from his/her vehicle.
For this reason, the countermeasures are taken such that the audio unit is constructed to have a unit main body and an operating part divided, for example, wherein the operating part is detachable with respect to the unit main body. When leaving the vehicle, the driver detaches the operating part from the unit main body to carry it with him/her. Since the unit main body cannot operate without operating part, there is no possibility of theft of the unit main body.
With the vehicle-mounted audio unit having an operating part detachable as described above, a conventional example of a mechanism for attaching and detaching the operating part to and from the unit main body is described in Japanese Patent JP-A 7-156719, which is constructed as follows:
As shown in FIGS. 10, 11, and 12, an audio unit 1 comprises a unit main body 2 and a front panel 3 as an operating part. The front panel 3 is provided with operating buttons 4 and a display 5, and is formed with a cassette opening 6b corresponding to a cassette loading mouth 6a of the unit main body 2. Moreover, connection terminals 7a, 7b are arranged for electrical connection upon mounting of the front panel 3.
Next, the structure for attaching and detaching the front panel 3 will be described. The unit main body 2 is formed with blind plate 8 for receiving the front panel 3 and a frame 8a at the periphery of the blind plate 8. There are arranged catching means 9 for catching one side or the right side of the front panel 3 and coupling means 10 for coupling another side or the left side of the front panel 3.
The catching means 9 comprise a pair of protrusions 11 formed on the frame 8 and a pair of engaging portions 12 formed with the front panel 3. The coupling means 10 comprise a mounting support plate 13, an arm 14, a holder 15, an extension coil spring 16 and a spring 17 normally elastically biased in the direction of center X as shown in FIG. 12, and an engaging recess 18 as shown in FIG. 11.
FIG. 14 shows the state of the front panel 3 attached. Since the arm 14 having a pin 14a and a release operating part 14b integrated therewith and formed out of synthetic resin is rotatable about pins 13a, and the spring 16 is greater in biasing force than the spring 17, the engagement is maintained between engaging portions 15a of the holder 15 mounted to the arm 14 to be rotatable about the pin 14a and pins 13b. Thus, an engaging portion 15b is engaged with the engaging recess 18, holding the attached state of the front panel 3.
When detaching the front panel 3, a release button 19 is pushed. Then, the release button 19 is protruded from the back of the front panel 3 (state in FIG. 13B) against a biasing force of a spring 20 to push the release operating part 14b. Then, the arm 14 is pushed backward against a biasing force of the spring 16 as shown in FIG. 15, in accordance with which the engaging portions 15a are disengaged from the pins 13b by a biasing force of the spring 17. The front panel 3 is pushed forward by a biasing force of the spring 17. Then, as shown in FIG. 16, the front panel 3 is pushed further forward by the action of the spring 17.
In the state in FIG. 16, the engaging portion 15b is engaged with the engaging recess 18, holding the attached state of the front panel 3. In this state, when taking the front panel 3 by hand and disengaging the engaging portion 15b from the engaging recess 18, the front panel 3 can completely be detached from the unit main body 2.
Next, when attaching the front panel 3, the pair of engaging portions 12 is engaged with the pair of protrusions 11 in FIG. 11, and then the left side of the front panel 3 is pushed in. Then, the engaging portion 15b is engaged with the engaging recess 18, attaching the front panel 3 to the unit main body 1 as shown in FIG. 14.
However, as seen from FIG. 14, since the coupling of the coupling means 10 is carried out by engaging the engaging portion 15b with the engaging recess 18, a large play between the two may cause falling out of the front panel 3 due to easy disengagement, while a small play may cause breakage of the engaging portion 15b and the engaging recess 18. Thus, fine combination verification is needed every time a metal mold of the front panel 3 is formed, leading to complicated and troublesome work.
Therefore, the present invention aims to provide attaching and detaching mechanisms which are free from such problem.